This invention relates to vapor compression refrigeration systems and, more particularly, to a subcooler within such systems for subcooling refrigerant.
Subcoolers have heretofore been used in vapor compression refrigeration systems to subcool refrigerant flowing from the condenser to the evaporator. Hot liquid refrigerant from the condenser typically passes through one or more orifices or nozzles located in the subcooler. These orifices or nozzles define a pressure drop between the condenser and the chamber of the subcooler. This pressure drop causes a portion of the liquid refrigerant to flash to vapor as it leaves the orifices or nozzles. The vapor refrigerant absorbs heat from the remaining liquid refrigerant passing into the chamber of the subcooler. The subcooler chamber may also include a condensing coil which circulates fluid having a temperature that recondenses the flashed vapor refrigerant. The recondensed refrigerant and the subcooled refrigerant exit the subcooler chamber for circulation through the evaporator. The above vapor compressor system is disclosed in U.S. Pat. No. 4,207,749 issuing to William J. Lavigne, Jr., on Jun. 17, 1980.
The orifices or nozzles of the aforementioned system are sized for a specific refrigerant flow that will create a particular pressure drop from the condenser into the subcooler chamber. The refrigerant flow is usually assumed to be the flow occurring at a full load condition for the vapor compression refrigeration system. This full load condition also assumes a particular entering condenser water temperature for the water circulating through the coil within the subcooler. The refrigerant flow to the orifices or nozzles will however drop as the full load condition on the refrigeration system drops. This drop in refrigerant flow will reduce the ability of the orifice or nozzle to produce the pressure drop needed to flash the refrigerant vapor in the subcooler chamber. This reduces the amount of cooling of refrigerant that may be provided by the subcooler. This in turn affects the overall efficiency and operating range of the refrigeration system.
It is an object of this invention to provide the necessary pressure drop through an orifice or nozzle within a subcooler so as to introduce sufficient flashed refrigerant vapor into a subcooler under a variety of operating conditions.